1. Field of the Invention
The present invention relates to a system for blind/attended transfer in a Session Initiation Protocol (SIP)-based network and a method of controlling the transfer.
2. Description of the Related Art
In a conventional Session Initiation Protocol (SIP)-based network, a blind transfer refers to transferring a call from a terminal B to a terminal C irrespective of reception of the terminal C when a terminal A, communicating with the terminal B, attempts to transfer the call to connect the terminal B with the terminal C, as shown in FIG. 1A.
An attended transfer refers to transferring a call from a terminal B to a terminal C after making a connection with the terminal C when a terminal A, communicating with the terminal B, attempts to transfer the call to connect the terminal B with the terminal C, as shown in FIG. 1B.
In a Public Switched Telephone Network (PSTN), a switch differentiates the two transfer schemes for call processing based on a hook flash signal and a hook on signal from a user. On the other hand, in an SIP-based network, a terminal differentiates the two transfer schemes for call processing since a server performs only processing associated with a message received from the terminal.
Since the two transfer schemes use a different call processing method, the terminal needs to have separate menus or buttons selected by a user to support the transfer schemes. However, a general terminal provides a soft menu so that the call transfer is performed only when a user selects the menu. The soft menu is displayed as a list of menus on a Liquid Crystal Display (LCD) screen, and one in the list is selected by a user pressing a corresponding button while scrolling.
The use of the soft menu to select the two transfer schemes is a tedious task to a user. The two transfer schemes cannot be provided by a terminal having no soft menu.